Like your comments RTS. This should happen all the way from Aberdeen to Plymouth. So you have locals in front from Aberdeen Edinburgh, Edinburgh Newcastle, Newcastle York, York Derby? Derby Birmingham, Birmingham Bristol, Bristol Plymouth and then the stopper folow the CC from Plymouth.
In the reverse direction the stopper is in front to Edinburgh and then follows to Aberdeen.
In the reverse there is an 1800 ScotRail to Dundee, unfortunately it's usually delayed by a local jeopardising the onward connection from
XC▸ at Aberdeen for Dyce and Inverurie - as a direct service from the North East (of England that is!) the train carries a lot of offshore workers needing the airport at Dyce.
Another irritation is that peak restrictions finish at 1809, the XC is 1810!